JOHANNESBURG, April 14 (Reuters) – South African utility Eskom said on Tuesday it had lost 9,500 megawatts (MW) of electricity due to unplanned outages, forcing it to implement widespread power cuts, in one of its most serious breakdowns in years.

Eskom said the 9,500 MW it lost was in addition to around 5,000 MW the utility had taken out for scheduled maintenance, meaning the utility is currently without about a third of its installed capacity of 42,000 MW.

However, the utility’s normal capacity is around 32,000 MW due to maintenance on some of its power plants.

"At this stage it is not clear how long it will take to fix the problem," Eskom spokesman Khulu Phasiwe said.

Earlier on Tuesday Eskom said it would need to take the rolling blackouts to "Stage 3," which means it needs to cut 4,000 MW.

Eskom has been forced to implement controlled power cuts in Africa’s most advanced economy this year to prevent the national grid from being overwhelmed.